Inferring temporal organization of postembryonic development from high-content behavioral tracking

Area of Science:

• Developmental biology
• Chronobiology
• Animal behavior

Background:

• Understanding temporal regulation in development is crucial.
• While average developmental timing is known, inter-individual variability is less understood.
• Postembryonic development in *Caenorhabditis elegans* offers a model to study developmental timing.

Purpose of the Study:

• To investigate inter-individual variability and correlations in the timing of postembryonic developmental events.
• To analyze the durations of larval stages in *Caenorhabditis elegans*.
• To identify distinct phases of postembryonic development based on timing variability.

Main Methods:

• Inferred larval stage durations (L1-L4) from locomotor activity patterns.
• Analyzed data from over 100 freely moving *Caenorhabditis elegans* individuals.
• Examined correlations between durations of successive larval stages.

Main Results:

• Individual development rates are consistent due to positive correlations in L1-L3 durations.
• The L4 larval stage shows less variability and is largely independent of earlier development rates.
• Larval stage durations exhibit scaling relative to total developmental time.

Conclusions:

• Postembryonic development in *C. elegans* comprises at least two distinct temporal epochs: early (L1-L3) and late (L4).
• Stage duration appears regulated by the completion of specific developmental events rather than fixed time.
• The described method provides a scalable platform for studying developmental timing.